The 1951 Elections were significant for Puerto Rico, as along side the ratification for the process for a constitutional convention, the Municipios of San Juan and Río Piedras voted as to whether become one Municipio - San Juan.
The Pretext of the unification vote was to abolish the - allegedly very corrupt - Municipio of Río Piedras, and, though Very controvercial there, the measure was approved in Río Piedras with a 5% margin, 52.5 in favor to 47.5% Against.
Furthermore, The expansion was approved in the Old Municipio of San Juan (Not to be confused with Viejo San Juan) with a Margin of 40.57% (70.29% in Favor, & 29.79 against), finding it's strongest support in Viejo San Juan with a 48.2% Margin in Favor of Ratification(74.1%-25.9%)
Despite the Alegations of Corruption that plagued Río Piedras, the measure succeeded in San Juan - and to a lesser extent in Río Piedras - thanks to the PPD Political machine of the legendary San Juan Mayor, Doña Fela (Felisa Rincón de Gautier), who campaigned hard for Condolidation.